Intrathoracic kidney

INTRATHORACIC ALVARO J. RAMOS, THOMAS JOSEPH

M.D.

L. SLOVIS, 0. REED,

KIDNEY

M.D.

M.D.

From the Departments of Radiology and Pediatrics, Children’s Hospital of Michigan, and Wayne State University School of Medicine, Detroit, Michigan

ABSTRACT - Five cases of intrathoracic kidney are presented, and the literature is reviewed. The because of upper respiradiagnosis was made incidentally in 3 patients who had chest radiographs tory tract infections and in 1 infant on a follow-up radiograph after recovery from hyaline membrane kidney, and disease. The fifth patient had an abdominal mass. All 5 patients had a left intrathoracic in the differential 2 had a left Bochdalek hernia. An intrathoracic kidney should be considered diagnosis of a posterior mediastinal mass.

An intrathoracic kidney is one of the least common of the renal ectopias.‘,’ Forty four cases of intrathoracic kidney have been reported in the English literaturels21 since the first documented case by Wolfromm in 1940.” In 15,919 autopsies of children, Campbell’ found 22 cases of ectopic kidneys, and only one was intrathoracic.

In the Mayo Clinic series of 21 children with renal ectopia who were seen consecutively during a twenty-four year period (1945-1969), only one had an intrathoracic kidneya An extremely rare case of bilateral intrathoracic kidney was recently described by Lundius.‘* One other case was previously described.3

FIGURE 1. (A) Frontal roentgenogram of chest reveals well-defined mass behind heart; margins are smooth and contours sharp, indicating it is extraparenchymal. (B) lateral view further conjrms extraparenchymal nature of lesion. (C) Oblique fdm obtained during intravenous urography reveals lesion to be high ectopic kidney; note elongated ureter and malrotation of kidney, and that inferior pole is closer to spine than superior pole.

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FIGURE 2. (A) Frontal chest roentgenogram reveals mass density in left retrocardiac region; it is not homogenous, and prediction of its exact nature is difficult. (B) Lateral view reveals posterior mass again, but here upper margin is more clearly defined as being extraparench ymal. (C) Frontal film during urography reveals mass to be high ectopic kidney; note again that kidney is malrotated and lower pole is closer to the spine than the upper pole. (D) Oblique view reveals pertrenal fat to advantage (arrows) and reveals hemidiaphragm above perirenal fat indicating its infradiaphragmatic position; note that calyceal system is more normal without any degree of dysplasia.

Intrathoracic kidneys occur more commonly on the left than on the right side, with 29 cases of left intrathoracic kidney and 12 on the right (2:l) and 3 cases of bilateral intrathoracic kidney. There is also a higher incidence in males than in females (3.6:1). Though rare, high renal ectopia should be considered in the differential diagnosis of mediastinal masses. Two males and three females comprise the present series. Their ages range from the neonatal period to three years five months at the time of diagnosis. All 5 patients had a left intrathoracic kidney; two also had a left Bochdalek hernia (Cases 3 and 4) and 1 patient had a hemangioendothelioma of the liver (Case

Case Reports Case 1 A black boy aged three years five months was seen in the outpatient department several times with a history of upper respiratory tract infection. The past medical history, growth and development, and findings on physical examination were normal. A chest radiograph revealed a density in the retrocardiac region (Fig. lA, B); intravenous urogram revealed the density to be an intrathoracic kidney (Fig. 1C). Case 2 This five-month-old Children’s Hospital

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bronchiolitis. Past medical history revealed that she was a full-term baby with normal growth and development. A chest radiograph revealed a posterior mediastinal mass (Fig. 2A, B); intravenous urogram demonstrated the mass to be a left intrathoracic kidney (Fig. 2C, D).

Case 3 A five-day-old white male, the product of a twin gestation and an uneventful vaginal delivery, was admitted to another hospital because of a palpable mass in the midabdomen. An intravenous urogram revealed an intrathoracic kidney (Fig. 3A, B). An upper gastrointestinal series the same day revealed extrinsic pressure along the lesser curvature of the stomach, most likely by an enlarged lobe of the liver. Chest radiography revealed a retrocardiac mass and high position of loops of bowel in the left upper quadrant. There was some indistinctness of the left dome of the diaphragm along the left costophrenic angle. At surgery, a left lobe hepatic hemangioendothelioma was excised. Examination of the left dome of the diaphragm disclosed a hernial sac, 4 cm. in diameter. The kidney, splenic flexure of the colon, and small bowel were within it. They were pushed down from the thoracic cavity, and the hernial sac was opened and transected. The diaphragmatic de-

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fect was then closed. The patient tory postoperative course.

had a satisfac-

Case 4 A nine-month-old black female was admitted to Children’s Hospital for an upper respiratory tract infection. Past medical history revealed that she had a left diaphragmatic hernia of Bochdalek repaired soon after birth at another hospital. After surgery, a residual density was noted at the base of the left lung. An intravenous urogram performed at this admission revealed a left intrathoracic kidney (Fig. 4A, B). Because of a history of repeated upper respiratory tract infections and inflammatory changes at the left lung base, a flood aortogram was performed to exclude the possibility of additional abnormalities such as a pulmonary sequestration (Fig. 4C). There were dilated left bronchial arteries with some extravasation of contrast material from one of the left bronchial arteries (upper arrow) into the lung tissue, consistent with inflammatory disease. In addition, the left renal artery was unusually long but had a normal origin (lower arrow). There was no pulmonary sequestration. A barium enema revealed recurrence of the left diaphragmatic hernia. Since the symptoms were minimal, surgical intervention is being planned electively.

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FIGURE 4. (A) Frontal chest roentgenogram reveals great deal of density behind heart. In addition to density, there is gas bubble at left lateral aspect of hemithorax; this is con* bowel sistent with hemithorax and recurrent di’,l phragmatic hernia. (B) Frontal urogram at this time reveals large segment of mass density to be high ectopic kidney. In addition, lateral to kidney, signiJcant inflammatory changes are seen in lung. On this film, bowel is not above Axis of kidhemidiaphragm. ney is abnormal with lower pole closer to spine. (C) Flood aortogram performed to exclude possibility of additional abnormalities such as pulmonary sequestration. Normal take-off of left renal artery is noted (lower arrow). In addition, there is pooling of contrast in left lung base (upper arrow). There is bronchial artery distribution to inflammatory changes in this region. No pulmonary sequestration was noted.

normally functioning kidneys without evidence of dysplasia, contralateral hypertrophy, or obstruction of the lower urinary tract. Thus, when renal ectopia is responsible for the intrathoracic kidney, an intravenous urogram would be all that would be indicated. The anatomic features of an intrathoracic kidney are (1) rotational anomalies, (2) a long ureter, (3) high origin of the renal vessels, and (4) medial deviation of the lower pole of the kidney.6’7 All of our patients had three of these anatomic features. One of our patients was studied angiographically and did not have a high origin of the renal vessels. In fact, Case 4 demonstrated a normal take-off of the renal artery. We have found that the calyceal pattern was variable, depending on the degree of malrotation of the kidney. The ipsilateral adrenal gland was not identified at the time of surgery in 2 of our patients (Cases 3 and 4). In the literature there is sparse mention of the ipsilateral adrenal gland, and in only 2 cases was the adrenal gland found to be ectopic in that it was located over the superior pole of the intrathoracic kidney.2J5

Case 5

This premature infant girl had severe hyaline membrane disease with opacification of both lungs (Fig. 5A). She received ventilatory assistance for several days. As she recovered, a mass density became apparent in the left hemithorax (Fig. 5B, C). When the infant was well enough to tolerate diagnostic studies, an upper gastrointestinal examination was done and findings were normal. Because of the posterior nature of the mass, an intravenous urogram was performed. The mass was found to be the left kidney (Fig. 5D). Comment A posterior mediastinal mass in a child frequently is a neoplastic lesion such as a neuroblastoma, ganglioneuroma, or neurofibroma. Further invasive procedures are indicated in these potentially surgical conditions. However, when ectopic viscera compose this mass, the approach is different. Renal ectopia of itself causes no symptoms. Intrathoracic kidneys are

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chest FIGURE 5. (A) Frontal roentgenogram at one day of age in premature infant reveals profuse changes of hyaline membrane disease -( obliterating subsequent findings of mass in retrocardiac region. (B) On recovery, extraparenchymal density was seen in retrocardiac region; smooth outlines of mass are apparent. (C) Lateral view again reveals extraparenchymal density in retrocardiac region. (D) Frontal urogram reveals malrotated, high ectopic kidney; note abnormal axis of kidney. Calyceal system is normal. Note perirenal fat (arrows) and diaphragm above perirenal fat. The reason for this high renal ectopia or intrathoracic kidney is uncertain. The kidneys differentiate from the intermediate or nephrogenic mesoderm. The adult kidney (metanephros) faces ventrad at first, then undergoes rotation of 90 degrees. This results from differential growth with more tubules being formed on the ventrolateral side than on the dorsomedial side. By this time, the adult kidney has reached its final location which is normally at the level of the second lumbar vertebra. Simultaneously with the rotation and “ascent” of the normal adult kidney, a complete closure of the diaphragm takes place. A maldevelopment of the pleuroperitoneal membrane might be responsible for an ectopic location of the intrathoracic kidney. 4-6 This is unlikely, however, since the incidence of intrathoracic kidneys with

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diaphragmatic hernias has been less than 0.25 per cent.g In addition, in most reported cases in which surgery or autopsy has been performed, there has been no evidence of a diaphragmatic tear or defect but rather a thin, membranous portion of the diaphragm has been found overlying the kidney. 4,7-11 This has also been demonstrated in 2 of our patients (Cases 2 and 5) in whom the diaphragm is seen above the kidney during total body opacification (Figs. 2D and 5D). It may well be that a diaphragmatic defect is secondary to the high position of the intrathoracic kidney.8 From review of the literature, and including our 5 cases, we have found that in only those cases with a diaphragmatic defect was the kidney above the diaphragm. 1*5*12-15,17 In some of these cases, a traumatic origin was

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suspected.5,‘2,i6 The remainder of reported cases in which surgery or autopsy was performed revealed an infradiaphragmatic location of the ectopic kidney. The segment of the diaphragm covering the high ectopic kidney appeared as a rather thin membrane.4,6-11 It appears to us that the final location of the kidney in cases of high renal ectopia will be supra- or infradiaphragmatic, depending on the presence of a concurrent diaphragmatic defect. Other mechanisms proposed for, the etiology of high renal ectopia such as the anomalous origin of the renal artery or as a part of a severe complex of congenital anomalies have been ne-

4. Barloon JW, Goodwin WE, and Vermooten V: Intrathoracic kidnevs. 1. Urol. 78: 356 (1957). 5. B&et NH: Right retroperitoneal diaphragmatic hernia, Br. J. Surg. 32: 421 (1945). 6. Spillane RJ, and Prather CC: Right diaphragmatic eventration with renal displacement, J. Urol. ‘i8: 804 (1952). 7. Condos B: High ectopy of left kidney, Am. J. Roentgenol. 74: 295 (1955). 8. Herth H, and Schahn N: Ectopic thoracic kidney, Israel J. Med. 5: 98 (1969). 9. Maher IJ and Stanley R: The intrathoracic kidney with a review of the literature, J. Ural. 107: 538 (1972). 10. Paul AT, Uragoda CG, and Tayewardene FL: Thoracic kidney with report of a case, Br. J. Surg. 47: 395 (1969). 11. Rubin EH: Diseases of Chest, Philadelphia, W. B. Saunders, 1948, pp. 533-535. 12. Budgen WF: Two cases of intrathoracic kidneys, Dis. Chest 17: 357 (1950). 13. Fusione D, and Molnar W: Anomalous pulmonary venous return, pulmonary sequestration, bronchial atresia, aplastic RUL, pericardial defect and intrathoracic kidney, Am. J. Roentgenol. 97: 350 (1966). 14. Franciskovic W, and Martincic N: Intrathoracic kidnev, Br. J. Ural. 31: 156 (1959). 15. Hill IE, and Bunts RC: Thoracic kidnev case rewrts. I1. I Urol. 84: 460 (1960). 16. Williams RG, and Tilhnghast AJ: Diaphragmatic hemiation of kidney, Radiology 53: 566 (1949). 17. Wolfromm MG: Position of the kidney in right diaphragmatic eventration, Mem. Acad. Chir. 66: 41 (1940). 18. Lundius B: Intrathoracic kidney, Am. J. Roentgenol. 125: 678 (1975). 19. Gray SW, and Skandalakis JE: Embryology for Surgeons, Philadelphia, W. B. Saunders Co., 1972, pp. 443-452. 20. Shapira E, Fisher LE, and Levin S: Intrathoracic kidney in a premature baby, Arch. Dis Child. 40: 86 (1955). 21. Moazzenzadeh AR, Khodadian P, and Potter RT: The intrathoracic kidney, J. Cardiothorac. Surg. 73: 480 (1977).

gated . 7,9,13,14,18,20 Children’s Hospital of Michigan Detroit, Michigan 48701 (DR. SLOVIS) To Dr. Frederick ACKNOWLEDGMENT. Case 3 and Dr. Victor Mikity for Case 5.

Cushing for

References 1. Campbell MF: Renal ectopy, J. Ural. 24: 187 (1930). 2. Malek R, Kelabs P, and Burke E: Ectopic kidney in children and frequency of association with other malformations, Mayo Clin. Proc. 46: 461 (1971). 3. Berlin HS, Stein JR, and Pope1 MH: Congenital superior ectopia of the kidneys, Am. J. Roentgenol. 78: 508 (1957).

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